The overall goal of the present project is to utilize rigorous experimental methodology and powerful contingent reinforcement procedures in natural environment studies with regular chronic smokers to meet the following objectives: 1) improve our understanding of the subjective effects of partial smoking reduction and abstinence; 2) evaluate the efficacy of potential aids to self-directed smoking cessation efforts; and 3) evaluate promising relapse prevention strategies. The first set of studies will utilize contingent reinforcement for lowered breath carbon monoxide levels to generate changes in smoking behavior. These studies will examine subjective effects, including craving, at several levels of partial smoking reduction, and will compare the subjective effects of partial reduction and smoking abstinence. A second set of studies will examine the behavioral effects of potential smoking cessation aids which could be conveniently disseminated at a worksite location. Cessation aids will be evaluated under standard motivational conditions for their ability to help smokers make further reductions in partially suppressed levels of smoking and/or to make cessation attempts. Specific cessation aids to be tested include nicotine gum, cigarette brand switching and participation in a lunchtime stop smoking club. A final study will evaluate a relapse prevention strategy designed for implementation at a worksite location which includes frequent carbon monoxide feedback and contingent reinforcement for maintenance of carbon monoxide levels in the nonsmoker range. Overall, these studies should result in improved understanding of the relative merits of gradual reduction versus abrupt cessation during quit smoking efforts as well as information about the efficacy of specific smoking cessation aids and relapse prevention strategies which can be conveniently implemented with smokers at worksite locations.